Air heating apparatus



Sfept. 24, 1935. B. E. SHAW ET AL AIR HEATING APPARATUS Filed July 2l,1934 5 Sheets-Sheet l HW AND ENEsr r M S5 R. E mED. m NNR m EO VTH A wwwR m @IW M Sept 24, 1.935l B. E. SHAW ET Al. 2,015,571

AIR HEATING APPARATUS Filed July 2l, 1954 5 Sheets-Sheet 2 n 2 y f' /a@'46 47, fz /7 A0 x@(7a i M v 7j i l l ,i l y 97 Q7 i 4 I"/0 7a M, 472'/7; ya :s j n Y m, Fig. 41 (/Z d 0f (/2 INVENTORS ATT RNEYS.BURMNESH/:w um

Sept. 24, 1,935. B, E. SHAW ET AL 2,015,571

AIR HEATING APPARATUS 4VRS y .BL/RTo/VESHAWANJ;

27m R/CHARDE. 55T

AT ORNEYS y gases from the primary radiator.

Patented Sept. 24, 1935 PATENT OFFIC 2,015,571 Am HEATING APPARATUSBurton E. Shaw,

Southwick, and Richard E.

Nest, West Springfield, Mass., assignors to Gilbert & BarkerManufacturing Company, West Springfield, Mass., a corporation ofMassachusetts Application July 21, 1934, Serial No. 736,290 4 claims..(01. 12s-t9) This invention relates to improvements in air heatingapparatus.

'I'he invention is capable of use in air heating apparatus of variousforms. It can, for example, be used to advantage in connection with awarm air furnace, especially in one of the type which is ired with oilor gaseous fuel and has, in addition to the primary radiator which isassociated. with the combustion chamber, a secondary radiator affordinga circuitous path of travel for the Or it can be used as a separate unitattached to any form of heater, serving as a booster or economizer toutilize the heat from the gases discharged from the main heater forraising the temperature of the air discharged from the heater (in casethe heater is a warm air furnace) or for heating a separate supply ofair. The invention is capable of use in any heating apparatus in whichit is desired to eiect a heat exchange between a conductor of hot gasesand an upwardly flowing stream of air.

The invention is directed to and has for one object the provision of aconductor for the hot gases of novel shape and construction,characterized in that it enables improved efliciency in the heattransfer between it andthe upwardly owing air stream.

The invention also has for an object the provision of baies whichcooperate with the aforesaid conductor and force theair into closecontact with the walls thereof, and promote smooth stream-line ow of theair without eddies at criticai points, whereby more air can be forcedthrough the apparatus in a given time by a fan, using a given amount ofpower, than can be forced through the various prior art apparatus withwhich we are familiar.

The invention also has for another object the use of baffles, for theabove named purpose, which are of trough-like formation capable ofcontaining water for use in humidifying the heated air.

The invention also has for an object the provision of a warm air furnaceof generally improved construction, having in particular a novel form ofsecondary radiator and having also a damper to control directcommunication between the primary radiator and the stack, such damperopening and closing automatically accordingly as the pressure within theradiator units is greater or less than a predetermined pressure.

These and other objects will more particularly appear asthe detaileddescription proceeds and will be pointed out in the appended claims.

The invention will be disclosed with reference to the accompanyingdrawings, in which:

Fig. 1 is a front elevational view of a furnace embodying the invention;

Fig. 2 is a sectional elevational view thereof;

Fig. 3 is a sectional plan view taken on the line 3,-3 of Fig. 1;

Fig. 4 is a cross sectional view taken on the line 4 2 of Fig. 1;

Fig. 5 is a sectional plan View taken on the line 5 5 of Fig. 1; and

Fig. 6 is a fragmentary cross sectional view taken on the line 6 6 ofFig. 1.

Referring to these drawings, in which the inven-tion has been shown asembodied in a warm air furnace, a casing I oi any suitable form isprovided. As herein shown, the casing includes a, framework composed ofa base II, upstanding columns I2 and horizontally disposed rails I3Ywhich interconnect the columns. The rails I3 support a top wall I4 whichis provided with an appropriate number of outlets I for the warm air.The spaces between the columns I2, rails I3 and base I I are enclosed byouter side wall sections I6 suitably secured thereto. Inner wallsections Il are suitably supported from the members II, l2 and I3 andprovide, with the outer side wall sections, air spaces I8 for insulationpur poses. Inlets I9 for cold air are provided on opposite sides of thecasing near one lower end thereof. The casing described affords arectangular enclosure in which allparts of the apparatus` are housed.

The cold air inlets I9 open into a chamber 20 (Fig. 2), formed byhorizontal and vertical partitions 2| and 22, respectively, which extendvtransversely across the casing fromy one inner wall Il to the other(Fig. 6), and are suitably secured thereto. Underlying and parallelingpartition 2l is a Wall 23 (Fig. 2) of less width, which extendstransversely from one inner side wall Il to the other and extendslongitudinally from the vertical partition 22 toward the adjacent innerend wall I1. The wall 23 terminates short of the adjacent end wall I'Iand is connected to an upwardly extending wall 24 having a saw-toothedupper edge 25 (Fig. 6). The wall 23 is provided with an opening leadinginto a fan chamber 26, formed between partition 22 and a U-shaped member21, which extends from wall 23 to the door. The vertical wall 24 andpartition 22 carry angle irons 28 from which a series of rectangular- 5such walls being spaced from the partition 21 (Fig. 6). The outlet 3I ofthe blower extends through the partition 22 near the lower edge thereof(Fig. 2) The drive shaft 32 of the blower extends through one wall ofpartition 21 and is driven by a belt 33 and suitable pulleys from anelectric motor 34 housed within chamber 20.

It will be clear that airis drawn in by the blower through the inlets I9into chamber 20 and, following the course of the arrows shown in Fig. 2,passes upwardly over the filters 29, thence downwardly through thesefilters into chamber 26, and thence into the inlets 39' of the blower,being expelled through outlet 3l into the remaining and L-shaped portionof the enclosure within the casing I9.

Within the vertical part of such L-shaped portion is an upstandingcylindrical shell 35, having in its lower portion a f'lre pot orcombustion chamber 36 and having its upper end closed except for acentral outlet for the gases. Above the fire pot 36, the shell 35 isprovided exteriorly with a circular series of radiating fins 31,encompassed by a cylindrical jacket 38 (Fig. 5). A horizontal partition39 (Fig. 4) extends transversely across the casing from one inner sidewall I1 to-the other and longitudinally from the vertical partition 22to the left hand inner end wall I1 (Fig. 2). This partition 39 has anopening therethrough equal in diameter to the internal diameter of thejacket 38. Air from the blower is received in the space below partition39 and encompasses the lower and fire pot section of shell 35. The airrises through the last named open- -ing and passes upwardly between theshell 35 and jacket 38 through the spaces between the fins 31, asindicated by the arrows in Fig. 2, and is heated in its passage by theprimary radiator, composed of the shell 35 and its fins. The air thenpasses to a secondary radiator to be later described. This shell and itsassociated` parts form the equivalent of a furnace and, in some cases,the invention may be practiced with a furnace of ordinary form which isa separate unit not housed in the same casing with the secondaryradiator.

The furnace unit may be fired in any suitable way although gas or liquidfuel is usually ernployed. As herein shown (Fig. 4), an oil burner ofthe gun type, designated 49, is employed as indicated in Figs. 1 and 4.The shell 35 has a side opening near its lower end in which is mounted aframe 4I having an opening to receive the nozzle end of the burner. Aplate 42, extending vertically from the partition 39 to the door (Fig.4) and longitudinally from partition 22 to the left hand inner end wallI1 (Fig. 5) divides off the space below partition 39 and provides acompartment 43 for the burner. Access to such compartment may be had byway of a removable panel or door 44 in the adjacent outer side wallsection IS.

The secondary radiator, with which this invention is more particularlyconcerned, comprises a plurality of substantially horizontally disposedpipes interconnected by headers, through which the gases of combustionflow in their course of travel to the stack and around the exterior ofwhich the air flows and is heated and, if desired, humidified as well.This, secondary radiator might be employed as an adjunct to the usualwarm air furnace, functioning as an economizeror booster, receiving thegases discharged from the furnace and heating air supplied from anysuitable source or superheating the air heated by the furnace, ifdesired.

lar but somewhat smaller parallel pipes 41, dis- '5 posed one on eachside of the central pipe. The open ends of these three pipes areconnected at one end to a header 48 in the form of a substantiallyrectangular box of sheet metal, and at the other end to a similar header49. The central 10 pipe 46, at a point close to header 49, has a shortdepending pipe 50, which is connected to the outlet in the top wall ofthe furnace unit 35. A U- shaped strap 5I serves to clamp the pipesection 50 against the top wall of the furnace and such 15 wall servesto support one end of the secondary radiator unit. The other end of suchunit is supported by a cross bar 52 (Fig. 6) which underlies the header48 and is in turn supported at its ends by hangers 53 from the siderails i3.

Mounted in pipe 46 is a delector 54 (Fig. 2). having a lower and dampersection 55 which is hinged at 56 thereto, as will be clear from Figs. 2and 4. The central part of header 49 has a depression 49' in its lowerWall of such form as to allow the damper 55 to swing freely to the leftas viewed in Fig. 2. The weight of the damper normally holds it in theposition shown.

The header 48 has a defiector 51, mounted centrally therein (Fig. 5) toassist in dividing the 30 gases, which flow to the right in pipe 46,into two streams which pass one to each of the pipes 41. The headers 48and 49 each have at each end a curved deflector 58 to assist in turningthe flow of gases from the header 4B into the pipes 41 35 or from thepipes 41 into the header 49, as the case may be. The deflectors 58 inheader 49 direct the gases inwardly toward the central outlet pipe 59which is connected at one end to they header and passes through theinner and outer side walls 40 I6 and I1, respectively, and is adaptedfor connection to the stack. The gases from the furnace unit risethrough pipe 50 into pipe 46 and normally pass to the right andtravelthrough a circuitous path, which includes the header 48, pipes 45 41 andheader 49, in order to reach the outlet pipe 59. However, on starting upthe burner, the initial puf will open damper 55 and allow the gases topass directly into the outlet pipe 59 and accelerate the draft. It mayfunction at other 50 times, if and when necessary, to relieve pressure.

The pipes 46 and 41 may each have mounted .loo'sely therein metal pieces6I of zigzag formation to retard the flow of gases therethrough. Handholes, covered by removable plates 62 are 55 vprovided in each header toenable these pieces to be inserted or removed and to allow access to theinterior of the headers and pipes for cleaning or other purposes. Thecombined area of the two pipes 41 is substantially greater than the areaof 60 pipe 46, thereby effecting a reduction of velocity of the gases inpipes 41 and affording greater time for these cooler gases to liberatetheir heat to the air.

Each of the pipes 46 and 41 has secured thereto 65 two sheet metal sidepieces 64 arranged in upwardly converging relation and intersecting in aridge located in the vertical plane which passes through the axis of thepipe. These pairs of plates form stream line shields for theirrespective pipes. The space between each such pair of pieces 64 a'ndtheir pipe 46 or 41, as the case may be, is closed of by end plates 65(Fig. 2) thus forming a dead air space 66. Cooperating with these plates64, which form a sort of roof of inverted V-form for their pipes, arebaffles 61 which are each mounted in spaced parallel relation with theadjacent plate. As shown, each pair of bailies 61 is connected by adeiiector wall 68. No baffles, such as 61, are shown cooperating withthe two outer plates 64 because they have not been found necessary but,obviously, baflles might be used at such locations if found desirable.

Each pair of members 61 and their connecting member 68 form a unit oftrough-like cross section and-these units may, in fact, be used astroughs to contain water where humidiflcation of the air is, as here, adesirable feature. In this event, the open ends Yof the two trough unitsare connected by two transversely disposed pans 69, one overlying eachheader, and supported therefrom by plates 10. Water may be supplied tothe pans and troughs in any of the ways well knownv to those skilled inthe art.

-An important feature of the invention resides in the shape andconstruction of the pipes d6 and 41 of the secondary radiator.Considering these conductors of hot gases as they appear in crosssection in Fig. 6, it will be seen that each is essentially a round pipesurmounted by a stream line shield comprising the upwardly convergingwalls S4. A round pipe is a standard article of commerce, easily andinexpensively manufactured, and lends itself readily to the use of thegas-flow retarders of zigzag formation. The shield is simply a sheet ofmetal bent into inverted V-shape and superposed on the round pipe andpreferably welded thereto, or otherwise secured, so as to insure a jointof good heat conductivity between it and the pipe. The ends of thisshield are preferably, although not necessarily, `closed off as shown bythe walls 65. While the pipe, in its gas conducting portion', might havethe same cross sectional shape interiorly as well as exteriorly,according to some features of the invention, the described arrangementis preferred.

With a round pipe crossing anupwardly owing air stream at right angles,the air impinges on the lower periphery of the pipe and splits into twostreams which ascend one on each side of the pipe. But these streams donot make effective contact with the upper peripheral portion of the pipewhich is naturally the hottest portion. The two streams, fiowingupwardly on opposite sides of the pipe, tend to create a vacuum abovethe pipe and eddy currents are created there, which present asubstantial resistance to air flow and materially interfere with anefficient transfer of heat from the hot upper portion of the pipe to theair streams. It is as if the air immediately above the pipe was pocketedthere in an area somewhat like that of the space 66. Air streams pass oneach side of this area, in which the eddies exist, but they areinsulated from the upper portion of the pipe by the pocketed air in thearea aforesaid. The shield, however, lls in this area in which the eddycurrents exist, and forms a good heat conducting substitute for thepocketed air. Smooth, stream-line flow of air, without eddies is securedand good contact between the walls 64 and the upwardly moving air issecured. The heat from the arc-like top part of the pipe which extendsbetween the lower edges of the shield, is carried oif by conduction,some to the lower part of the pipe and some to the walls 64 of theshield. These walls-64 conduct heat from the top wall of the pipe tolocations where an effective transfer of the heat to the air can bemade. Thus, in a broad sense, the invention puts in the place of an areaoccupied by air, either pocketed or moving in eddies, and in any eventof poor heat conductivity, a shield of good heat conductivity. The air,occupying the said area, heretofore blanketed off the upper portionofthe pipe from the upwardly moving air streams and preventedari-efficient heat transfer. With this invention, not only are the eddycurrents eliminated at the said area, but a good conductor of heat isplaced there where it can come into close contact with the upwardlymoving air streams. 10 'I'he bailles 61 are, of course, very desirablein that they force the air streams into close contact with walls 64 andpromote smooth, stream iiow but, while desirable, they are neverthelessnot indispensable. So also the use of these baffles as 15 water troughsis an important and desirable but, nevertheless, not indispensablefeature of t'le invention.

Actual tests made with the same apparatus with and without the shield64, show that more 20 air can be forced through the apparatus in a giventime with the same power applied to fan 30, when the shield is used.These tests also show that the stack temperature is lower when theshield is used, thus indicating that more of the 25 heat has beenextracted from the gases and that a more eifective heat transfer iseffected. That more air can be forced through the apparatus when theshield is used, without the use of more power, is due to the eliminationof the eddy cur- 30 rents described and the vresistance which theypresent to air flow. Thus, a greater volumeof air can be delivered withthe same amount of power and this greater volume heated Vwith the sameburner because more of the heat from the burner 35 is utilized when theshield 64 is used.

What we claim is:

1. In an air heating apparatus, a casing having near the lower partthereof an inlet for the air to be heated and near the upper partthereof an outlet for the heated air; a fan for causing air to flow intothe inlet, upwardly in the casing and outwardly through .said outlet; aradiator unit located within said casing and including a pipe forconducting hot gases and extending substantially horizontally across thepath of the up- 4 wardlyowing air, said pipe having exteriorly an upperportion in the cross sectional form ofan inverted V and a lower portionin the cross sectional form of an arc connecting the free ends of theinverted V-shaped portion, and a bale on each side of said upper portionto direct the upwardly owing air after it has been divided by the lowerportion of the pipe into smoothly flowing streams along the upwardlyconverging walls of said upper portion.

2. In an air heating apparatus, a casing having near the lower partthereof an inlet for the air to be vheated and near the upper partthereof an outlet for the heatedair; a fan for causing air to ow intothe inlet, upwardly in the casing and outwardly through said outlet; aradiator unit located within said casing and including a pipe forconducting hot gases and extending substantially horizontally across thepath of the upwardly flowing air, a shield of inverted v formsurmounting the upper part of the pipe, and a baille on each side ofsaid shield to direct the upwardly flowing air after having been dividedby the lower portion. of said pipe into two ,o smoothly flowing streamsalong the upwardly l converging walls of said shield.

' 3. In an air heating apparatus, a casing having near the lower partthereof an inlet for the air to be heated and near the upper p artthereof 75 CII surmounting the upper part of the pipe and having closedends to form within the shield and between it and the upper part of saidpipe a dead air space, and a bame on each side of said shield to directthe upwardly owing air after having been divided by the lower portion ofsaid pipe into two smoothly owng streams along' the upwardly convergingWalls of said shield.

4. In an air heating apparatus, a casing having near the lower partthereof an inlet for the air to be heated and near the upper partthereof an outlet for the heated air; a fan for causing air to flow intothe inlet, upwardly in the casing and outwardly through said outlet; aradiator unit .located within said casing' and including a pair ofsubstantially parallel pipes for conducting hot gases and extendingsubstantially horizontally across the path of the upwardly owing air,each of said pipes having exteriorly an upper portion composed ofupwardly converging walls and a lower portion connecting the free endsof said walls, the adjacent upper portions of said pipes presenting apair of upwardly diverging walls, and a baie interposed between 10 saidupwardly diverging walls and having upwardly extending portions oneadjacent but spaced from each of the last-named walls forming there witha slot for the 'stream line ow of air along its wall and a connectingportion to block of! 15 the .flow of air except through said slots andform with the upwardly extending portions a trough for containing waterto humidify the heated air.

BURTON E. SHAW. RICHARD E. NEST.'

